Safety cut-off system for use in walk-behind power tool

ABSTRACT

A safety cut-off system prevents the running of a motor of a self-propelled lawn mower having left and right drive wheels, and forward and reverse gears. The safety cut-off system includes a first forward presence lever manipulatable, by an operator, between an ON state and an OFF state, wherein the forward presence lever is biased to the OFF state, and a reverse presence lever manipulatable, by an operator, between an ON state and an OFF state, wherein the reverse presence lever is also biased to the OFF state. A preventing element, which is responsive to the forward and reverse presence levers, is provided for preventing the motor from running, when the lawn mower is in neutral or a forward gear and neither the forward presence lever nor the reverse presence lever are in the ON state, and when the lawn mower is in a reverse gear and the reverse presence lever is not in the ON state.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a walk-behind power tool, such as alawn mower, snow blower, power sweeper or like equipment, andparticularly to a self-propelled walk-behind power tool. Moreparticularly, this invention is directed to a safety cut-off system forpreventing the running of a motor under certain conditions when thepower tool is left unattended. Furthermore, the instant invention ismore particularly directed to a system of presence levers indicating thepresence of an operator, for controlling the safety cut-off system.

2. Description of the Related Art

Although the present invention has utility in walk behind snow blowers,power sweepers or the like, the most common utilization of the inventionis anticipated for walk-behind type, lawn mowing equipment andparticularly in self-propelled, large capacity mowers of the commercialtype. Consequently, except where otherwise expressly stated, thedescription herein is directed to walk behind lawn mowing equipment andparticularly commercial type lawn mowers.

Commercial type, self-propelled, walk-behind lawn mowers, commonly havea power deck containing two drive wheels and handle bars for supportingthe operating handles or the various mower control elements. The mower,or tool deck, which connects with the power deck, carries idler (orcaster) wheels to support and balance the mower deck.

In most cases, such mower decks are detachable with respect to the powerdeck. As stated above, snow blowers, power sweepers and the like may beused with this power deck. Our description will refer specifically tothe lawn mower deck to be used with the power deck, but the explanationapplies also to a snow blower, power sweeper or other auxiliary unit.Specifically, because the mower deck is detachable from the power deck,a power take-off unit is provided to transmit power from the power deckto the mower deck. Thus, the motor, on the power deck, provides power todrive the drive wheels, as well as power to drive the auxiliary unit, orthe mower deck itself. While many types of power take-off units may beused to transmit power from the power deck to the mower deck, for thepurposes of this description, a drive belt will be described, fortransferring power from the power deck to the mower deck. Furthermore, apower take-off lever is provided on the handle bar for engaging anddisengaging the power take-off unit. Additionally, presence (or deadman) levers are provided on the handle bars.

Mower safety has increasingly been an important factor in the design anddevelopment of todays lawn mowers. A current ANSI requirement for amower with a power take-off (PTO) unit, is that the engine must becut-off when the machine is unattended. In order to provide for this,mowers in the past have used a presence lever. When the operator isusing the mower, the presence lever is grasped along with the handle ofthe handle bar. When the operator leaves the mower, if the motor andpower take-off are both engaged, when the presence lever is released, asthe operator walks away, the engine is cut-off.

A problem that occurs in prior art devices is that, often the samepresence lever is used for forward and reverse. In some cases, it maycreate an awkward control situation in which the presence lever must begrasped the same way to pull the mower backwards as to push the mowerforward.

SUMMARY OF THE INVENTION

The present invention is intended to overcome the disadvantages andproblems described above. The safety cut-off system of the instantinvention meets the ANSI requirements that the engine be cut-off whenthe PTO is engaged and the lawn mower is unattended. Further, theinstant invention provides for a separate reverse presence lever whichmust be engaged (in the ON state) in order to prevent the cut-off of themotor when the PTO is engaged.

In particular, the instant invention is directed to a safety cut-offsystem for preventing the running of a motor of a self-propelled lawnmower having left and right drive wheels and forward and reverse gears.The safety system includes a first forward presence lever shiftable, byan operator, between an ON state and an OFF state, wherein the forwardpresence lever is an biased to the OFF state. It also includes a reversepresence lever shiftable, by an operator, between an ON state and an OFFstate, wherein the reverse presence lever is biased to the OFF state. Apreventing means is also provided which is responsive to the forward andreverse presence levers, for preventing the motor running, when the lawnmower is in neutral or forward gear and neither the forward presencelever nor the reverse presence lever are in the ON state, and when thelawn mower is in reverse gear and the reverse presence lever is not inthe ON state.

In other words, when the lawn mower is in the reverse gear, it isrequired that the reverse presence lever be in the ON state (beingengaged) in order to prevent the motor from being cut-off. If the lawnmower is in the neutral or forward gear, then either the forwardpresence lever or the reverse presence lever may be in the ON state (inthe engaged state) in order to prevent the motor from being cut-off.

In another feature of the instant invention, the safety cut-off system,described above, is applicable to a lawn mower system having two forwardcontrol levers, each controlling the power output to a separate drivewheel. In such a case, a separate presence lever is provided for each ofthe two forward control levers. Because the control handles (or levers)have a large range in motion, and the presence lever must be easy touse, the forward presence lever, corresponding to one of the controlhandles, must be close to the control handle so that the operator maygrasp the presence lever and the control handle together, when movingthe control handle forward to apply power to the drive wheels.Accordingly, the forward presence levers are advantageously pivotedabout a pivot point fixed with respect to the forward control handles.

Furthermore, the fixed handle bar onto which the control handles andother control elements are mounted, includes a generally horizontal endportion, for pushing and pulling the lawn mower. For moving the mower ina reverse direction, first the gear shift lever must be placed inreverse gear, and then the reverse control handles (or lower controlhandles) must then be pulled in the rearward direction in order toprovide power to the drive wheels in the reverse direction. The lowercontrol handles (or reverse control handles) are merely an extension (inthe downward direction) of the forward control handles. The controlhandles are pivoted at a point intermediate the upper control handle(forward control handle) and the lower control handle (reverse controlhandle). Accordingly, to control the amount of power provided to thedrive wheels, when the upper control handle (forward control handle) ismoved forward, the power to the drive wheels is increased. Accordingly,because the pivot for the control handle is intermediate the uppercontrol and the lower control handle, when the upper control handle ismoved forward, the lower control handle is automatically pivotedrearward. Thus, the gear shift determine the direction (forward orreverse) of the drive to the drive wheels, while the control handles(upper or lower control handles) determine the amount of power deliveredto the drive wheels.

The horizontal end portion of the fixed handle bar is arranged in aproximal position to the lower control handles such that an operator maybe able to grasp the lower handles and the horizontal end portion of thefixed handle bar for pulling the lawn mower in reverse. Accordingly, areverse presence lever is provided near, and preferable above, thehorizontal end portion of the fixed handle bar. When the fixed handlebar is grasped to pull the lawn mower in reverse, the reverse presencelever may easily be pressed down to be substantially adjacent thehorizontal end portion of the fixed handle bar. Thus, it is relativelyeasy to engage the reverse presence lever while grasping the horizontalend portion of the fixed handle bar and also pulling the lower controlhandle (or handles) rearward for movement in a reverse direction.

It is most normal for an operator to grasp the horizontal portion thefixed handle bar, along with the reverse presence lever with both hands,generally spread apart. Since the reverse presence lever is mostly usedonly when the lawn mower is in reverse, it is possible that the operatormay lean over the handle bar and his clothing or stomach mayunintentionally press down upon the reverse presence lever when theoperator does not intend for that to happen and is trying to stop themower. Accordingly, to prevent such an occurrence, a presence leverguard is provided for preventing unintentional engagement of the reversepresence by a portion of the operator's physique or his clothing.

The guard includes a central plate extending generally upwardly from acenter portion of the horizontal end of the handle bar, wherein thecentral plate is located between the reverse presence lever and anoperator behind the handle bar. The central plate is oriented generallyperpendicularly to a direction of travel of the mower. Furthermore, theguard includes a top plate extending generally forward from a top edgeof the central plate, such that the top plate extends substantially overa portion of the reverse presence lever. Furthermore, the top plate ofthe guard is spaced apart from the horizontal end portion of the handlebar, such that there is sufficient room for the reverse presence leverto rest, above the horizontal end portion of the handle bar, in the OFFstate. Thus, the presence lever guard helps to prevent unintentionalengagement of the reverse presence lever.

Accordingly, the safety cut-off system according to the instantinvention provides for an easily operated system which complies withcertain ANSI safety requirements. Because the reverse presence levermust be engaged (in the ON state), in order for the motor to beoperatable when in reverse gear, it is believed that this is animportant safety feature. The reverse presence lever is comfortable forthe operator to use and it is convenient to use, therefore it promotesits use by operators.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a self-propelled, walk-behind formof lawn mower incorporating the present invention;

FIG. 2 is a rear perspective view of the lawn mower of FIG. 1;

FIG. 3 is a side elevational view, partly in section, of the lawn mowerillustrated in FIG. 1;

FIG. 4 is a partial side elevational view of the handle bar andcontrol-operating handles mounted thereon employed on the mower of FIG.1;

FIG. 5 is a partial perspective view illustrating in greater detail thecontrol elements and the controlled element shown in FIG. 4;

FIG. 6 is another partial perspective view of the control elements andthe elements controlled thereby shown in FIG. 4;

FIG. 7 is a view taken along line 7--7 of FIG. 4;

FIG. 8 is a plan view of the belt and pulley system employed foroperating the drive wheels of the present invention;

FIG. 9 is a partial perspective view of the power deck with drive leversand parking brake operator mounted thereon;

FIG. 10 is a rear view of the power deck and drive levers of FIG. 9;

FIG. 11 is a partial elevational view with portions removed taken alongline 11--11 of FIG. 8;

FIG. 12 is a perspective view of the parking brake operator elements ofthe present invention;

FIG. 13 is a schematic view illustrating parking brake operator elementsin various positions;

FIG. 14 is a partial perspective view of the operating handle andpresence lever for forward operation of the drive wheel on the rightside of the lawn mower shown in FIG. 1;

FIG. 15 is a view similar to FIG. 13 showing the operating handle andpresence lever for reverse operation of the drive wheel on the rightside of the lawn mower shown in FIG. 1;

FIG. 16 is a schematic representation of the control circuitry for thelawn mower of the present invention;

FIG. 17 is a partial perspective view of the blade brake and operatingelements thereof for the lawn mower of the present invention; and

FIG. 18 is a more detailed partial perspective view of the blade brakeand operating elements thereof shown in FIG. 16.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention has application to power tools of variousforms, such as snow blowers, power sweepers, or the like, the drawingfigures illustrate an embodiment of the invention in which the operationelement of the power tool is a lawn mower, particularly one employingmultiple rotary blades as is common in large capacity, commercial formsof lawn mowing equipment. Also, although the disclosed lawn mower isdescribed as being a "walk-behind" lawn mower, the concerned inventionis equally applicable to power equipment attaching a "sulky" or aplatform on which the operator may ride.

The described lawn mower 10, as best shown in FIGS. 1 to 3, contains apower deck 12 and a tool-or mowing-deck 14. Desirably, the mowing deck14 is detachably connected to the power deck 12 to permit substitutingfor the mowing deck, either a snow blowing apparatus or a power sweepingapparatus, neither of which is shown herein.

The power deck 12 contains a bed 16 defined by a generally rectangularsheet metal plate 18 having downturned flanges 20, 22 and 24 withflanges 20 and 22 being disposed along the laterally spaced sides of thebed, and flange 24 extending between, and interconnecting, the sideflanges at the rear of the bed. An engine 26 is mounted on the uppersurface of the bed 16 wherein a through-opening 28 is provided toaccommodate passage of the engine drive shaft 30 to the underside of thebed plate 18. An inverted U-shaped bracket 32 has its down-turned legs32a and 32b secured to the rear end of the bed 16 and its upwardlydisposed platform portion mounting a fuel tank 34.

A pair of laterally spaced drive wheels, including left wheel 36 andright wheel 38, are disposed on opposite sides of the bed 16 in a mannerhereinafter more fully described. Also, a pair of laterally spacedsupport arms 40 extend longitudinally forward from the bed 16 forattaching the mowing deck 14. The support arms 40 are fixedly secured attheir respective rear ends to the bed and at their forward ends eachmount left and right caster wheels 42 and 44, respectively, which arejournalled for free rotation about a vertical axis by associated supportshaft housings 460. As shown best in FIG. 3, the mowing deck 14 ismounted via laterally spaced brackets 448 carrying pivot pins 450 whichpivotally engage the respective support arms 40 adjacent the forwardends thereof. A height adjusting mechanism 452 secures the rear end ofthe mowing deck 14 in a manner which permits height adjustment of themowing deck.

As shown in FIGS. 4, 5 and 6, a handle bar 56 having a pair of left andright depending arms 58 and 60, respectively, is fixedly secured to thedownturned legs of the bracket 32. A panel plate 62, that issubstantially coextensive with the space along the handle bar 56 betweenthe arms 58 and 60 provides access to control elements, as hereinafterare more fully described.

Drive Controls

With particular reference to FIGS. 3 to 11 of the drawings, lawn mowercontrol apparatus is shown for controllably operating the left and rightdrive wheels 36 and 38. The control apparatus includes individual leftand right gear-operated transmissions 64 and 66, respectively. Thetransmissions are mutually spaced laterally with respect to each otherand each has a horizontally extending output shaft (not shown) extendingin opposite directions away from each other with each output shaft beingadapted to mount a hub of one of the drive wheels 36, 38. Thetransmissions are structurally interconnected on their respective facingends by means of appropriate connecting structure (not shown) and arefixedly secured to the bed 16 of the power deck 12 by means ofconnectors (not shown) that attach posts which surround an output shaftbearing bushing 72 to laterally extending support ears 74 fixedlysecured to the respective side flanges 20 and 22 of the power deck bed16. Power input to each transmission 64, 66 is effected by a belt-driveninput pulley, indicated as 76 on the left transmission 64 and as 78 onthe right transmission 66. Each pulley 76 and 78 is fixed to androtatably drives input shafts on the respective transmissions 64, 68 andextends substantially parallel to the engine drive shaft 30.

As indicated in FIGS. 4, 5, 7 and 8 of the drawings, the engine driveshaft 30, which rotates about a vertical axis, mounts a pair ofvertically spaced pulleys 80, 82, about the respective ones of which thedrive belts 84, 86 extend. Drive belt 84 extends between the uppermostpulley 80 on the engine drive shaft 30 and the pulley 76 on the inputshaft to the left transmission 64. Drive belt 86 extends between thenext lower pulley 82 on the engine drive shaft 30 and the pulley 78 onthe input shaft to the right transmission 66. As shown, the input pulley76 on the left transmission 64 is disposed slightly higher than pulley78 on the right transmission and substantially level with the pulley 80on the engine drive shaft 30. Similarly, the input pulley 78 on theright transmission 66 is disposed substantially level with the pulley 82on the engine drive shaft whereby the drive belts 84 and 86 each operatein substantially level, horizontal planes.

A third pulley, termed "the power take-off (PTO) pulley," 88 is disposedat the lower end of the engine drive shaft 30 and is engaged by a drivebelt 90 employed to rotatably drive the mower blades, as describedhereinafter.

Belt guards, in the form of rod members 91 attached at one of their endsto the bed 16, have offset portions positioned closely adjacent thevarious belts and serve to prevent the respective belts from becomingdislodged from the pulleys which they engage.

Power input to the respective drive wheel transmissions is individuallycontrollable by means of clutch element 92, 94 which are each in theform of idler pulleys 96, 98 that rotate on one end of pivotable leverarms 100, 102, respectively, whose opposite ends are pivotally securedto the undersurface of the metal bed plate 18. As shown best in FIG. 7,the lever arms 100, 102 which carry the respective idler pulleys 96, 98are each disposed within the space surrounded by the drive belt withwhich each is associated. Return springs 129 which have one endconnected to the bed 16 and the other end connecting each lever arm 100,102 serve to normally bias the idler pulleys 96, 98 away from theirrespective drive belts 84, 86. Also, appropriate limit stops (not shown)extend from the bed plate 18 and serve to limit the angulardisplacements of the lever arms 100, 102 when they are pulled intodisengagement by the return springs 129.

Each of the wheel drive transmissions 64 and 66 is a multi-speed gearedtransmission which produces discrete selected speeds that the panelplate 62 indicates by notches 104 as best shown in FIG. 5, and includefour forward speeds, a reverse speed and a neutral position. A tandemcontrolled transmission shifting device 105 (FIG. 8) is operative tojointly change the gear of the respective transmissions 64, 66. Gearedtransmissions, suitable for use in the practice of the invention, arethose made by Dana Corp. under Model No. 4360-102.

Separate control members operate the clutch elements in order to varytorque transmission between the output of the engine drive shaft 30 andthe input to the respective left and right drive transmissions 64, 66.Thus, as shown in the drawings, the bracket 32 on the power deck 12mounts a support shaft 106 which extends between, and is fixed at itsends, to the respective legs 32a and 32b of the bracket. Drive levers108 and 110 having the general shape of an inverted J and disposed ataxially spaced locations along the shaft 106 contain clearance openingsin the legs of the levers which enable the levers to undergo controlledpivoted movement about the shaft. Spacers 112 serve to separate thedrive levers 108, 110 from the respective legs 32a, 32b of the bracket32. Each of the drive levers 108, 110 is independently operated by arespective one of a pair of control handles 114, 116 which are disposedfor pivotal movement on the handle bar 56 and that contain transverselyextending upper portions to facilitate manual manipulation by themachine operator. A connecting rod 118 extends between and connects therespective control handles 114, 116 to each drive lever 108, 110. Axialadjustment of the respective connecting rods with respect to theirassociated drive lever can be effected by a turnbuckle 120 whichconnects an upper portion 118a to a lower portion 118b of eachconnecting rod.

Each drive lever 108, 110 attaches at a depending leg portion a drivespring 122 which extends forwardly from the drive lever and is generallyaxially stiff. The springs 122 have at one end a hook 124 that engagesan opening 126 in the depending leg of the drive lever 108 and 110. Theother end of each spring 122 contains an elongated loop 125 forming alost motion space and that, with regard to the left idler pulley 96,engages a pin 127 which depends from the underside of the lever arm 100.With regard to the right idler pulley 98, and in order to accommodatethe unequal vertical spacing between the drive belts 84 and 86, thelooped end 125 of the associated spring 122 engages the lower end ofbent pin 128 whose upper end is fixed, as by means of welding, or thelike, to the edge of the right idler pulley lever arm 102.

Thus, operation of the mower in the forward direction involves, first,the transmissions 64 and 66 associated with the respective wheels 36 and38 being placed by the operator in a selected drive range, as determinedby placement of the shift lever 130 in an appropriate notch 104 in thepanel plate 62. To propel the mower straight forwardly both uppercontrol handles 114a and 116a are simultaneously moved forwardlywhereupon the drive levers 108 and 110 are pivoted about the supportshaft 106 in a direction to extend the drive springs 122 rearwardlywhich causes the lever arms 100 and 102 carrying the idler pulleys 96and 98 to be controllably urged into engagement with the respectivedrive belts 84 and 86 thereby adjusting the tension of the respectivedrive belts about the pulleys they engage. Such adjustment alters thetorque transmission from the engine drive shaft 30 to the left and righttransmissions 64 and 66, respectively, within the selected gear range.To steer the mower 10, the operator need only push or pull one controlhandle with respect to the other whereupon the driving force to onedrive wheel with respect to the other is altered thereby causing thecourse of the machine to be altered.

Reverse propulsion of the mower 10 is accomplished by, first, moving theshift lever 130 to the reverse position in the notches 104. Then, thelower control levers 114b and 116b of the control handles 114 and 116are pulled rearwardly. This rearward motion of the lower control handles114b and 116b has the same effect as the forward motion of the uppercontrol handles 114a and 116a. The mower 10 may be steered in reverse inthe same manner as the forward driving.

Braking of the respective drive wheels 36 and 38 in order to stopforward movement of the machine, or to augment its turning movements, iseffected by the operator pivotally moving one or the other, or both ofthe control handles 114 and 116 in a direction opposite to that requiredfor effecting rotation of the drive wheels 36, 38 for forward movement.Thus, to brake the left drive wheel 36, for example, the control handle114 which controls operation of the left drive wheel is pivoted, eitherby pulling its upper control handle 114a backwardly or by pushing itslower control handle 114b forwardly. By imparting such movement to thecontrol handle 114, the connecting rod 118, which interconnects the leftcontrol handle 114 with the left drive lever 108, causes the drive lever108 to rotate in a clockwise direction, as viewed in FIG. 11, whereuponthe left brake lever 134 which connects to the drive lever 108 viaconnecting link 135 is pivoted in a clockwise direction about pivot pin136 to cause brake band 138 whose ends connect with the brake lever viapin connectors 140 to constrict the brake pad 142 about the brake drum144 on the wheel. Note that the brake drum 144 for the left wheel 36 hasbeen omitted for clarity and that FIG. 11 shows only the brake drum 144that is connected to the right wheel 38.

The connecting link 135 includes an elongated loop 135a that forms alost motion coupling with the drive levers 108 and 110. This loop 135aallows the drive levers 108 and 110 to rotate counterclockwise (asviewed in FIG. 11) to engage the idler pulleys 96 and 98 with theirrespective drive belts 84 and 86 without imparting further motion ontothe brake levers 134 which would cause further separation of the brakebands 138 from the brake drums 144.

The simultaneous braking of both drive wheels 36 and 38 is effected byperforming the above-described operation simultaneously on both controlhandles 114 and 116. Alternatively, in order to augment turning of themachine, one of the drive wheels can be substantially fully, or onlypartially, braked while the other drive wheel continues to be drivenforwardly so as to effect a tight turn.

It will be appreciated that the power tool drive apparatus describedherein, utilizing gear-operated drive transmissions, produces operatingcharacteristics and features which heretofore were unique to equipmentemploying hydrostatic transmissions for transmitting engine power to thedrive wheels. The disclosed arrangement provides a compactness of formwhich enables all of the components, which define the drive train, to beenclosed by the power deck bed, thus to protect the drive traincomponents against damage occurring from the components contacting treelimbs or other vegetation, or the like. Conversely, by enclosing thedrive train components, the machine operator and others who might comein close proximity to the machine are protected against injury caused bycontact with moving drive train components.

These and other advantages previously attributable to hydrostatictransmissions are effectively obtained from gear-operated transmissionsby practice of the invention wherein the clutching function, that isrequired for the use of gear-operated transmissions, is effected by theengagement of idler wheels on the drive belts, which engagement occurson belts that transmit drive torque from the engine to the input to thetransmission instead of to the output of the transmission as has beenthe practice of the prior art. As a result, because the clutchingfunction is imposed on drive belts subjected to high speed but lowtorque, as contrasted with the converse, which prevails with prior artbelt driven machines of the concerned type, undue wear caused by beltslippage is avoided. Therefore, the frequency of belt replacement, withits attendant inoperability of the machine, is significantly reduced.

Undue stressing of drive belts utilized in the described machine isfurther reduced by the fact that the idler pulleys are caused to engagethe associated belts on the inside surface of the belts, i.e., the samesurface as is engaged by the driving and driven pulleys of the system.Thus, compressive stresses are continuously imposed upon the inside beltsurface while the outside belt surface is continuously stressed intension. These continuous stress conditions are contrasted with priorart devices wherein, due to the idler pulley engaging the concernedbelts on the side opposite that engaged by the drive and driven pulleys,the belts undergo the alternate imposition of compression and tensionstressing which results in increases in belt fatigue and rapid beltwear.

Safety Cut-Off System

The safety cut-off system in accordance with the instant invention willbe described in connection with the figures set forth below.

FIGS. 1-6 illustrate the overall view of the mower including thearrangement of the handle bar controls. As illustrated in FIGS. 4-6,left forward presence lever 201 and right forward presence lever 202 aredisposed near left upper control handle 114a and right upper controlhandle 116a. Furthermore, the generally elongated shape of left forwardpresence lever 201 and right forward presence lever 202 generallyfollows the elongated shape of upper left control handle 114a and upperright control handle 116a. Furthermore, as noted in FIGS. 5 and 6, thegenerally elongated shape of reverse presence lever 203 is similar tothe elongated shape of the generally horizontal end portion 57 of handlebar 56. As seen in FIGS. 3 and 4, in profile, left forward presencelever 201, right forward presence lever 202 and reverse presence lever203 are generally flat so that they may be easily be grasped togetherwith another bar. Left forward presence lever 201 is easily graspedtogether with left upper control handle 114a, while right forwardpresence lever 202 is conveniently grasped together with upper rightcontrol handle 116a. Accordingly, reverse presence lever 203 isconveniently grasped together with horizontal end portion 57 of handlebar 56, in addition to lower control levers (or reverse control levers)114b and 116b.

FIG. 14 is a partial perspective view isolating right forward presencelever 202 along with its corresponding upper right control handle 116aand lower right control handle 116b. Specifically, as noted, rightforward presence lever 202 generally follows the shape of upper rightcontrol handle 116a. Accordingly, wherever it is possible to grasp upperright control handle 116a, right forward presence lever 202 is alsoeasily grasped at the same time. Because the control handle 116 ispivotable with respect to handle bar 56 through a relative large angle,right forward presence lever 202 is pivotably mounted directly to theright control handle 116. In fact, since right forward presence lever202 pivots with respect to right control handle 116, it is always nearto upper right control handle 116a, no matter how little or how farupper right control handle 116a is pivoted. Normally open, right forwardsensor switch 208 is fixed with respect to right control handle 116.Furthermore, a switch arm 204 extends generally forwardly from rightforward presence lever 202 and is fixed with respect thereto. A spring206 is provided between right forward presence lever 202 and upper rightcontrol handle 116a, such that right forward presence lever 202 isbiased in the OFF state (disengaged state) and thus switch arm 204 isnot engaged with plunger 210. When right forward presence lever 202 isgrasped together with upper right control handle 116a, that is, theright forward presence lever 202 is now in the ON state (engaged state)switch arm 204 accordingly pivots and presses down plunger 210 of switch208. This action causes switch 208 (which is a normally open switch) tobe closed and thus to conduct electrical current between contacts 212,to which control wires are connected. The arrangement of the leftforward presence lever with respect to the left control handle 114 issubstantially a mirror image of the right forward presence lever 202 andright control handle 116, illustrated in FIG. 14. FIG. 3 illustratesleft forward presence lever switch 220 which is opposite the rightforward presence lever sensor switch 208.

FIG. 15 illustrates the relationship between the reverse presence lever203 and handle bar 56. Handle bar 56 is fixed with respect to the mower.Also, as seen in FIGS. 5 and 6, the generally horizontal end portion 57of handle bar 56 is generally parallel with reverse presence lever 203.Reverse presence lever 203 is pivoted with respect to handle bar 56.When reverse presence lever 203 is grasped together with horizontal endportion 57 of handle bar 56, reverse presence lever 203 is substantiallyadjacent horizontal end portion 57 of handle bar 56. A reverse presencelever switch arm 216 extends downwardly from reverse presence lever 203and is adaptable to engage plunger 222 of reverse presence lever sensorswitch 214. When reverse presence lever 203 is in the OFF state, it isbiased away from horizontal end portion 57 of handle bar 56 by spring218. Reverse presence lever sensor switch 214 is a normally open switch.Thus, when reverse presence lever 203 is in the OFF state (disengagedstate) reverse presence lever sensor switch 214 is maintained open. Whenthe reverse presence lever 203 is grasped together with horizontal endportion 57 of handle bar 56, switch arm 216 is pivoted to contactplunger 222 and accordingly to close sensor switch 220.

FIG. 16 is a schematic diagram of the control circuit layout forcontrolling the safety cut-off system in response to the operation ofthe presence levers and control levers. Reference numeral 240 generallyrefers to the circuit for controlling the safety cut-off system. Circuit240 is connected to connection block 236 with labeled connections B-F.Connection block 236 is in turn connected to switching module 238, whichis available from Alphabet Wire Harness as Model No. 135331. Of course,module 238 may be any type of a switching module with relays, switches,electronic switches, a programmed logic array, or any other appropriateswitching device.

Engine magneto 234 is connected to key switch 230 and is also connectedto contact B. Key switch 230 is normally open when the engine isrunning. The opposite side of key switch 230 is connected to ground,thus when key switch 230 is closed, the engine magneto is grounded andthe mower is prevented from running. On the side of key switch 230,opposite the engine magneto, key switch 230 is also connected to contactE. An hour meter 232 is connected between contact points B and E.Contact point C is connected to a front side of reverse gear sensorswitch 226 (normally closed) and to the front side of reverse presencelever sensor switch 214. The back side of reverse gear sensor switch 226is connected to a first lead of left forward presence lever sensorswitch 220 and in parallel to a first lead of right forward presencelever sensor switch 208. The first lead of left forward presence leversensor 220 is also connected to a first lead of power take-off sensorswitch 228 (normally closed). The second lead of power take-off sensorswitch 228 is connected to contact D. The second lead of left forwardpresence lever sensor switch 220 is connected to contact F. The secondlead of right forward presence lever sensor switch 208 is connected to asecond lead of reverse presence lever sensor switch 214 and to contactF.

During operation, in its most basic sense, one or both of the forwardpresence levers 201, 202 are pushed forward (into the ON state) when thelawn mower is neutral or forward gear, and while pushing forward on theupper control handles 114, 116. When the lawn mower is in reverse gear,the reverse presence lever 203 is depressed onto the horizontal endportion 57 of handle bar 56, while pulling backward on lower controlhandles 114b, 116b. Module 238 functions to connect contact E (at groundpotential) to contact B to provide a ground level signal to the enginemagneto and thus prevent the motor from running. When contact C isconnected to contact D or F, then the connection between contact B andcontact E is broken, and thus contact B is no longer at groundpotential, therefore enabling the motor to run.

As noted, reverse gear sensor switch 226 is normally closed. This meansthat when reverse gear is engaged, switch 226 becomes open. When switch226 becomes open, the only way for contact C to conduct to contact F isthrough reverse presence lever sensor switch 214. In order words, theonly way to prevent cutting-off of the motor is to engage (put into theON state) the rear presence lever 203. Thus, if the gear shift is in thereverse gear, irrespective of the status of right forward presence leverswitch 208, left forward presence lever switch 220 and power take-offsensor switch 228, the reverse presence lever sensor switch 214 must beclosed in order to prevent a cut-off of the motor.

When the lawn mower is in neutral or a forward gear, reverse gear sensorswitch 226 is closed. Accordingly, any one of reverse presence leversensor switch 215, left forward sensor switch 220, or right forwardsensor switch 208 may be closed (either of the two forward presencelevers or the reverse presence levers in the ON state) in order toprevent contact B (and thus the engine magneto) from being grounded.

Power take-off lever sensor switch 228 is normally closed. That is, whenthe power take-off unit is engaged, the switch is open, and when thepower take-off unit is disengaged then switch 228 is closed.

A clear view of how the schematic diagram of FIG. 16 works can be seenwith reference to the following table A.

                  TABLE A                                                         ______________________________________                                                           Right   Left                                               No.  Gear   PTO    Fwd PL  Fwd PL  Rev PL  Engine                             ______________________________________                                        1    N-4    ON     OFF     OFF     OFF     OFF                                2    N-4    ON      ON (OFF)                                                                             OFF (ON)                                                                              OFF (ON)                                                                              ON                                 3    N-4    OFF    OFF (ON)                                                                              OFF (ON)                                                                              OFF (ON)                                                                              ON                                 4    R      OFF    OFF     OFF     OFF     OFF                                5    R      OFF     ON (OFF)                                                                             OFF (ON)                                                                              OFF     OFF                                6    R      OFF    OFF (ON)                                                                              OFF (ON)                                                                              ON      ON                                 7    R      ON     OFF     OFF     OFF     OFF                                8    R      ON      ON (OFF)                                                                             OFF (ON)                                                                              OFF     OFF                                9    R      ON     OFF     OFF     ON      ON                                 ______________________________________                                    

As can be seen from Table A, the different status of the right forwardpresence lever, the left forward presence lever and the reverse presencelever affect the engine depending on which gear is selected and whetherthe power take-off unit (PTO) is engaged (ON) or disengaged (OFF).Specifically, items 1-3 illustrate the situation in which the gearselector is in neutral or forward gears 1-4. In this situation, if thePTO is on, the engine will be prevented from running if neither theright forward presence lever 202, the left forward presence lever 201nor the reverse presence lever 203 are in the ON position. Item 2indicates that if one of the three presence levers is ON, then the motoror engine will not be prevented from running. Item 3 indicates that ifthe PTO is OFF and neutral or a forward gear is selected, then theposition of the presence lever does not matter and the engine is notprevented from running.

Items 4-9 indicate the situation in which the lawn mower is in reversegear. As can be seen in items 4-9, whether the PTO is ON or OFF, theonly condition which will allow the motor to be ON is when the reversepresence lever 203 is also in the ON state.

A presence lever guard 490 is attached to the handle bar 56 as shown inFIGS. 3-5. This guard 490 has a central plate 492 extending upwardlyfrom a center position on the horizontal end portion 57 of the handlebar 56. A top plate 494 extends generally forwardly from the top edge ofthe central plate 494 and substantially over a portion of said reversepresence lever 203.

The reverse presence lever 203 is free to move within the space definedby the horizontal end portion 57 and the presence lever guard 490.However, the presence lever guard prevents inadvertent operation of thereverse presence lever by the operator because the presence lever guardis positioned between the operator and the reverse presence lever.

Parking Brake

The disclosed mower includes a parking brake assembly identifiedgenerally by reference numeral 300 and described with particularreference to FIGS. 9, 11, 12 and 13 of the drawings. The parking brakeapparatus for the respective drive wheels 36 and 38, includes the drivelevers 108, 110, which operate to constrict the brake bands 138 aboutthe hubs of the respective drive wheels through activation of brakelevers 134 by the respective drive levers and connecting links 135 whichrigidly connect the brake levers to the drive levers.

The parking brake assembly 300 includes an operating shaft 302 whichextends laterally across the rear of the bed 16 of the power deck 12,with the opposite ends of the shaft being mounted for rotation inopenings 146 formed in the side flanges 20 of the bed plate 18. A pedalarm 304 having a foot pedal 306 attached at its free end is fixedlysecured to the operating shaft 302, whereby the operating shaft iscaused, when activated, to rotate in a counter-clockwise direction, asviewed from the right hand end in FIG. 12.

As shown in the drawing figures, each drive lever 108, 110 has a pawl308 in the form of an inclined U-shaped projection extending from a sidesurface of a depending leg of the drive lever. The operating shaft 302contains a pair of locking fingers 310 and 312, each of which containsan upwardly facing side edge 314 having an arcuately formed portionadjacent the free end and having locking teeth 316 thereon adapted toengage the pawls 308. In order to facilitate engagement of the pawls 308on the drive levers 108, 110 with the locking teeth 316 on the lockingfingers 310, 312, the free ends of the teeth are arcuately formed. Also,as shown in FIG. 13 which illustrates a drive lever 108, 110 in both ofits extreme positions of engagement with the locking levers, theinclination of the pawls 308 and the disposition of the teeth 316 alongthe locking finger edge 314 is such as to ensure a full surfaceengagement of the pawl with the teeth wherein the engagement forcevectors are substantially normal to the engaging surface on the pawl, asindicated by direction lines 318 and 320.

According to the invention, the locking finger 310 is fixed, as by meansof welding, to the operating shaft 302 so as to rotate with the shaft. Areturn spring 321, which is connected at one end to a hole 322 in thelocking finger 310 and whose other end is fixed with respect to the bed16, biases the locking finger 310, and consequently the shaft 302, in adirection away from the drive levers. This bias is overcome when thefoot pedal 306 is depressed.

Locking finger 312 is connected to the operating shaft 302 in a manneras to permit a restricted amount of relative movement with respect tothe shaft in order to provide a lost motion function between the lockingfinger and the shaft. As shown, the locking finger 312 has a clearancehole 324 through which the operating shaft 302 loosely passes. A pair ofradially extending pins 326 and 328 are fixed to the shaft at axiallyspaced locations therealong. Pin 326 is positioned closely adjacent theright side of locking finger 312, as viewed in FIG. 12, and pin 328 islocated at a position remote from the left side of the locking finger. Atorsion spring 330 surrounds the operating shaft 302 between the leftside of locking finger 312 and the radial pin 328. A tang 332 on theright end of the torsion spring 330 attaches the locking finger 312 viaa connecting hole 334 therein. The left end of the torsion spring 330contains an arm (not shown) which bears against radial pin 328. Duringassembly of the torsion spring onto the shaft, the spring is pre-loadedin a tightening direction so as to bias the movable locking finger 312upwardly toward the adjacent pawl 308, with such upward movement beinglimited by engagement of the tang 332 with the radial pin 326.

As is evident from consideration of FIG. 12, the locking fingers 310 and312 are not angularly aligned about the operating shaft 302. Instead,the movable finger 312 is displaced angularly upwardly with respect tothe fixed finger 310 so as to engage the pawl 308 on drive lever 108prior to engagement by the fixed finger 310 with the pawl 308 on drivelever 110. As a result of this construction, depression of the footpedal 306 by the machine operator causes, first, the teeth 316 on themovable locking finger 312 to engage the pawl 308 on the drive lever 108in order to lock the drive lever, and concomitantly, the associatedbrake lever 134 in their counter-clockwise positions to hold the brakeband 138 constricted about the brake drum 144 of the left drive wheel.Immediately, thereafter, the fixed locking finger 310 is brought intoengagement with the pawl 308 on drive lever 110 so as to secure thedrive lever in its braked condition, limited continued rotation of theoperating shaft 302 being permitted due to the lost motion functioneffected by the coupling of locking finger 312 to the operating shaft302 through the torsion spring 318.

The operation of the described parking brake assembly 300 is as follows.When the drive control handles 114 and 116 that connect with drivelevers 108 and 110, respectively, are pulled backward by the machineoperator, the brake bands 138 constrict brake pads 142 about the brakedrums 144 to apply a braking force to the respective drive wheels 36,38. The residual forces developed in the brake bands 138 bias thecontrol handles 114 and 116 to a neutral position on the handle bar 56,which position is intermediate their "drive" position and their "brake"position. Coincident with this, drive levers 108, 110 and theirassociated brake levers 134 tend to move in a counterclockwise directionas viewed in FIG. 11.

The parking brake function is initiated by the machine operatordepressing the foot pedal 306 with the wheel brakes being manuallyapplied and the control handles 114, 116 being held by the operator intheir "brake on" or rearward position. Consequently, operating shaft 302is rotated counter-clockwise to move the locking fingers 310, 312 towardthe pawls 308 on the respective drive levers 108, 110 whereupon lockingteeth 316 on the movable locking finger 312, which is upwardly biasedout of alignment with fixed locking finger 310, are caused to engage thepawl 308 on the drive lever 110. With the torsion spring 330 providing alost motion coupling between the movable locking finger 312 and theoperating shaft 302, the shaft continues to rotate until the lockingteeth 316 on the locking finger 310 engage the pawl 308 on drive lever110.

A force perpendicular to the end face of the pawl 308 results when theteeth 316 engage the pawl 308. This force is the result of theinclination of the pawl 308 and the bias on the drive lever 108, 110 torotate clockwise. The direction of this force is represented in FIG. 13by lines 318 and 320 for the two positions illustrated.

The force generated between the teeth 316 and the pawls 308 is directedover the pivot (i.e., the center of the operating shaft 302) of thelocking fingers 310 and 312. This force tends to rotate the lockingfingers 310 and 312 upwardly (counterclockwise). However, the pawls 308,which are attached to the drive levers 108 and 110, tend to rotateclockwise to the "neutral" position of the drive levers 108 and 110.Thus each engaged member has a force applied to it that biases eachmember further into engagement.

This perpendicular force creates a frictional force between the engagedtooth 316 and the pawl 308. The frictional force is perpendicular to theforce along line 318 or 320. The frictional force counteracts the forceof the return spring 321 attached to the locking finger 310. Theinteraction of the perpendicular force, the friction force and thereturn spring force creates a self-locking relationship between thepawls 308 and the locking fingers 310 and 312. Therefore, the parkingbrake assembly remains engaged.

For releasing the parking brake, the machine operator pulls the controlhandles 113, 116 rearwardly. Such action causes movement of the drivelevers 108, 110 in a clockwise direction which results in the pawls 308being removed from engagement with the locking teeth 316. When thisoccurs, the force resisting the return spring 321 is removed and thefixed locking finger 310 falls away from its associated pawl 308 therebymoving with it the operating shaft 302 and the movable locking finger312 whereupon the parking brake becomes fully disengaged.

From the foregoing, it is evident that the described parking brakeorganization is of simple, inexpensive construction, yet is effectivefor its intended purpose and, moreover, as compared with comparabledevices of the prior art, permits location of the parking actuator in anuncongested, easily accessible location on the mower.

Blade Brake Assembly

The blade brake assembly in accordance to the instant invention isoperated when the power take-off unit is disengaged. Specifically (asseen in FIG. 17), the power take-off unit includes a power take-off(PTO) drive pulley 88 driven by the motor, and PTO drive belt 90 drivenby the PTO drive pulley 88. Mower deck drive pulley 428 is engaged withPTO drive belt 90 and is driven by it. Mower deck drive pulley 428 isattached to and co-axial with shaft 430 which drives the center mowerblade. A mower deck drive belt 436 is threaded around center mower deckpulley 444, immediately beneath mower deck drive pulley 428 and alsosupported on shaft 430. The mower deck drive belt 436 is also threadedaround right side mower deck pulley 440, which is supported on shaft 434which also support the right side mower blade. The mower deck drive belt436 is furthermore threaded around left side mower deck pulley 442 whichis disposed immediately beneath the blade brake assembly 446 and issupported on left side shaft 432 which also supports the left side mowerblade. A mower deck tension pulley 438 provides proper tension on mowerdeck drive belt 436 for driving all three mower blades. PTO idler pulley414 is inserted in contact with PTO drive belt 90 between PTO drivepulley 88 and mower deck drive pulley 428. When PTO idler pulley 414 isengaged with PTO drive belt 90 and is biased outwardly, the powertake-off unit is engaged and the mower deck drive pulley 428 is driven.When PTO idler pulley 414 is shifted inwardly (as shown in phantom) sothat it no longer applies tension on PTO drive belt 90, the powertake-off unit is disengaged. In other words, mower deck drive pulley 428is not driven.

PTO idler pulley 414 is shifted inwardly to disengage the PTO unit. PTOidler pulley 414 is shifted inward in response to PTO control lever 402,as best seen in FIGS. 6 and 17. PTO control lever 402 is connected byway of upper rod 404 to first arm 406. First arm 406 is fixed withrespect to second arm 408 by way of collar 410. Collar 410 is supportedby and rotates around shaft 106. Second arm 408 is connected by way oflower rod 412 to a lower mounting fitting 427. Furthermore, a dampingspring 422 is provided on a remote end of lower rod 412, on the oppositeof lower mounting fitting 427 from second arm 408. An idler pivot 420fixed to the power deck includes first PTO idler arm 416 and second PTOidler arm 418. First PTO idler arm 416 extends outwardly from idlerpivot 420 and rotatably supports PTO idler pulley 414. Second PTO idlerarm 418 extends outwardly from idler pivot 420 and provides a mountingsurface for lower mounting fitting 427 which provides for a pivotalconnection with rod 412. An upper mounting fitting 426 is provided onthe upper portion of second PTO idler arm 418. In response to themovement of rod 412, second PTO idler arm 418, and in turn first PTOidler arm 416 pivots about idler pivot 420, thus causing PTO idlerpulley 414 to move inwardly (as shown in phantom) and outwardly withrespect to the PTO drive belt 90. Belt guide 424 is simply provided toprevent PTO drive belt 90 from slipping off of PTO idler pulley 414 asit releases its tension and moves inwardly with respect to the belt.Thus, when PTO idler pulley 414 is shifted inwardly, the PTO unit isdisengaged.

As illustrated in FIG. 3, the lawn mower having a blade braking systemin accordance with the instant invention is adjustable for differentcutting heights. Specifically, as seen in FIG. 3, the mower deck 14 isillustrated in its high position. It is also illustrated in its lowposition 15, as indicated in phantom. The lawn mower is supported on theground by drive wheels 36, 38 in the rear and by caster wheels 42, 44 inthe front. Support arms 40 are fixed with respect to the power deck 12.At the forward end of support arms 40, the caster wheels 42, 44 aresupported. A support shaft housing 460 is fixed to the forward end ofeach support arm 40, and supports a caster support shaft 458 therein.Support housing 460 is adjustable up and down along the length of castersupport shaft 458, in order to raise and lower support arms 40 withrespect to the caster wheel and the ground. Preferably, spacers 480 (seeFIG. 2) may be inserted or removed from below each support shaft housing460 in order to raise or lower it with respect to the associated casterwheel. Mower deck 14 is mounted to support arm 40 by way of a pair ofbrackets 448 (FIG. 17) which are supported on support arm 40 by way ofpivot pin 450 (FIG. 3) being inserted in opening 451 of bracket 448(FIG. 17). While the left side is being described, it should be notedthat the right side is similar.

As illustrated in FIGS. 3 and 17, a height adjusting mechanism isgenerally indicated by the arrow 452 and includes a pivot bar 454 whichpivots (through angle 453) with respect to support arms 40 and has aninwardly extending engaging end 455. Pivot bar 454 pivots about a pivotportion 451 (see FIG. 17). The engaging end 455 supports bracket 456which is fixed to the top of the lawn mower deck. As seen in FIGS. 2 and3, a deck height lever 482 is fixed to a forward end of pivot bar 454.Deck height lever extends upwardly with a remote end easily grasped byan operator. A notched adjustment track 484 is in interlockingengagement with deck height lever 482, wherein deck height lever 482 isincrementally shiftable with respect to notched adjustment track 484into one of a number of predetermined positions indicated by a notch innotched adjustment track 484. Each predetermined position represents adifferent cutting height. Since deck height lever 482 is fixed to pivotbar 454, as deck height lever 482 is pivoted, pivot bar 54 pivots orrotates (through angle 453) with respect to support arm 40, and inwardlyengaging ends 455 shift downwardly with respect to support arm 40. Sinceengaging ends 455 support brackets 456 and thus mower deck 14, asengaging ends 455 shift downwardly, so do brackets 456 and accordinglymower deck 14. However, mower deck 14 is pivoted at pivot pin 450 (FIG.3). Thus, the mower deck pivots downwardly and does not remain levelwith respect to the ground. This causes two concerns. The first concernis maintaining the mower deck and the mower blade in a positionsubstantially parallel to the ground. This is accomplished by adjustingthe height of support shaft housing 460 with respect to caster support458. Therefore, when the mower deck 14 is adjusting downwardly orupwardly by the height adjusting mechanism 452, the support shafthousings 460 are also adjusted to compensate.

A second concern arising from the pivoting deck is the proper connectionof a linkage to the blade brake for braking the mower blades when thePTO unit is disengaged. This solution will be described below.

When the PTO is disengaged, then ANSI regulations require the blades tostop moving within specified amount of time. Thus the blade brake shouldbe applied when the lawn mower is shifted into the PTO disengaged state.Accordingly, as illustrated in FIG. 17, actuating rod 462 is connectedto second PTO idler arm 418 by way of pivotable upper mounting fitting426. Actuating rod 462 extends forwardly from second PTO idler arm 418to pivot lever 464. Pivot lever 464 pivots about a center pivot 466which is fixed to mower deck 14 (illustrated as 14' in FIG. 18). Pivotlever 464 (as seen in FIGS. 17 and 18) transfers the longitudinalreciprocating movement of actuating rod 462 indicated by arrow a intothe longitudinal reciprocating movement of link member 468 indicated byarrow b. Center pivot 466 and pivot lever 464 are fixed to the mowerdeck at a point near the mower deck pivot pin 450 which pivots inopenings 451 of brackets 448. As noted in FIG. 18, the forward end ofactuating rod 462 has a connecting end 476 extending generallyperpendicular to the actuating rod 462. Connecting end 476 is insertedinto an oversize hole 478 such that actuating rod 462 is pivotable intwo different angular directions with respect to pivot lever 464.Actuating rod 462 pivots in a direction generally parallel to the planeof the pivot lever 462 as indicated by arrow c. Furthermore, because ofthe oversize hole 478 and the connecting end 476 of actuating rod 462,actuating rod 462 is also pivotable in a direction not parallel to theplane of pivot lever 464. In fact, actuating rod 462 is pivotable in adirection generally perpendicular to the plane of pivot lever 464 asindicated by arrow f. Link member 468 extends from a pivotal connectionwith a second end 474 of pivot lever 464 to connect with band brake 446.A support ring 470 (FIG. 17) is fixed to the mower deck to support anend of link member 468 nearest the band brake. As link member 468 shiftstoward the band brake, the band brake is applied, braking the left mowerblade and the other mower blades by way of mower deck drive belt 436. Asillustrated in FIG. 18, it is preferable that the distance between thecenter pivot 466 and the connection of pivot lever 464 with actuatingrod 462 indicated by d2 is greater than the distance from center pivot466 to the connection between pivot lever 464 and link member 468(indicated by d1). Since the pivot lever 464 is located near pivot pin450 of the mower deck, the pivotability of actuating rod 462 in twodifferent angular directions compensates for the pivoting of the mowerdeck when raising and lowering the height adjustment. Furthermore,because actuating rod 462 is a long rod and pivoted at pivot lever 464,any large change in lateral movement of actuating rod 462 at the endnearest the power deck is reduced to a smaller amount near pivot lever464. Furthermore, when d2 is greater than d1, any difference inlongitudinal motion of actuating rod 462 (between high and low cuttinglevels) is accordingly reduced in the longitudinal motion of link member468. Thus, the pivoting movement of the mower deck when changing cuttingheight is compensated for without requiring continued adjustment of theblade brake itself, and thus enabling the blade brake to always be inproper alignment, since it is fixed with respect to the location ofcenter pivot 466 and pivot lever 464.

In operation, when the operator moves the PTO control lever 402 toselect a disengaged state for the PTO unit, motion is transmittedthrough upper rod 404, first arm 406, collar 410, second arm 408, lowerrod 412, through lower mounting fitting 427 to pivot second PTO idlerarm 418 about idler pivot 420. When idler pivot 420 pivots in theclockwise direction, first idler arm 416 and PTO idler pulley 414,rotatably attached thereto, are pivoted in turn. As PTO idler pulley 414is shifted inwardly, the tension on PTO drive belt 90 is removed andpower to mower deck drive pulley 428 is removed. As second PTO idler arm418 moves forwardly, so does actuating rod 462, because it is pivotallyconnected to second PTO idler arm by way of pivotable upper mountingfitting 426. As actuating rod 462 moves forward, pivot lever 464 pivotsabout center pivot 466 and causes link member 468 to be movedlongitudinally toward band brake 446 and thus apply band brake 446 tothereby stop the rotation of the mower blades.

When the PTO control lever 402 is returned to the engaged state toengage the PTO unit, each of the above elements operates in the reverseway to release band brake 446 and thus to allow the mower blades to spinfreely.

Ballast System

The ballast system in accordance with the instant invention can best beseen with reference to FIGS. 3-6. Ballast tank 252 is illustrated inthese figures. The ballast system in accordance with the instantinvention is used with a lawn mower 10 having a power deck 12 and amowing deck 14. An engine or motor 26 is positioned on bed 16 of powerdeck 12 for driving left and right drive wheels 36, 38. Mower deck 14 isattached to and extends forwardly from power deck 12 and is supported atits front end by caster wheels 42, 44. A fuel tank 34 is supported onbracket 32 located at the rear portion of power deck 12. Depending arms58, 60 extend upwardly and rearwardly from the power deck and are fixedto and supported by bracket 32. Ballast tank 252 is supported betweendepending arms 58, 60 of the handle bar 56. As seen most clearly inFIGS. 3 and 4, ballast tank 252 is disposed near the end of handle bar56, remote from power deck 12. FIGS. 3 and 4 illustrate a filler cap 254or opening the top of ballast tank 252 to fill the interior volume withthe desired ballast, whether water, sand or any other appropriateballast. Draining cap 256 allows the ballast to be easily drained outfrom ballast tank 252.

As clearly seen in FIG. 3, ballast tank 252, disposed near an end ofhandle bar 56, is located behind the center line of drive wheels 36, 38.In fact, the ballast tank 252 is disposed behind the rearmost portion ofdrive wheels 36, 38. Furthermore, it should be noted that ballast tank252 is disposed at least partially behind fuel tank 34.

In operation, the filler cap 254 may simply be removed by the operatorand ballast tank 252 may be filled with water, sand or any otherappropriate ballast. Cap 254 may then be replaced. The appropriateballast in ballast tank 252 will change the center of gravity of thelawn mower itself. It will aid to counter balance the mower deck 14attached on the front of the power deck 12. This will aid in handlingthe lawn mower in tight places, or under any other circumstances.Because ballast tank 252 is disposed high up on handle bar 56, in orderwords, near the end of handle bar 56, this arrangement increases themovement arm of any ballast in ballast tank 252, thus increasing theefficiency of any such ballast. When finished, the user may drain theballast through drain cap 256.

It should also be noted that although the above description has been setforth with regard to the mower deck 14, the power deck 12 may also beemployed with a snow blower, auxiliary unit, a power sweeper auxiliaryunit or many other types of auxiliary units. As an example, the lawnmower deck may have a different weight than the snow blower auxiliaryunit or the power sweeper auxiliary unit. Accordingly, because theballast tank 252 has an interior volume that may accept varying amountsof ballast, the ballast tank 252 may be filled full, or may be partiallyfilled to compensate for different weights of the different auxiliaryunits, such as the mower deck, the snow blower auxiliary unit and thepower sweeper auxiliary unit.

Although a specific form of embodiment of the instant invention has beendescribed above and illustrated in the accompanying drawings in order tobe more clearly understood, the above description is made by way ofexample and not as a limitation to the scope of the instant invention.It is contemplated that various modifications apparent to one ofordinary skill in the art could be made without departing from the scopeof the invention which is to be determined by the following claims.

We claim:
 1. A safety cut-off system in combination with aself-propelled lawn mower for preventing the running of a motor of theself-propelled lawn mower having left and right drive wheels, andforward and reverse gears, said safety cut-off system, comprising:afirst forward presence lever operatively mounted on a handle bar of thelawn mower and being manipulatable, by an operator, between an ON stateand an OFF state, said forward presence lever being biased to the OFFstate; a reverse presence lever operatively mounted on the handle bar ofthe lawn mower and being manipulatable, by an operator, between an ONstate and an OFF state, said reverse presence lever being biased to theOFF state; and preventing means, operatively connected to said presencelevers and the motor and being responsive to said forward and reversepresence levers, for preventing the motor from running,when the lawnmower is in neutral or a forward gear and neither said forward presencelever nor said reverse presence lever are in the ON state, and when thelawn mower is in a reverse gear and the reverse presence lever is not inthe ON state.
 2. The safety cut-off system of claim 1, wherein the lawnmower includes a power take-off lever operatively connected to saidpreventing means and having ON and OFF positions, for engaging anddisengaging power to a power take-off unit, wherein said preventingmeans is also responsive to the position of said power take-off lever.3. The safety cut-off system of claim 2, further comprising a secondforward presence lever operatively mounted on the handle bar of the lawnmower, being operatively connected to said preventing means and beingmanipulatable, by an operator, between an ON state and an OFF state,said second forward presence lever being biased to the OFF state, leftand right control handles mounted on the handle bar and operativelyconnected to said left and right drive wheels, respectively, said firstand second forward presence levers corresponding to said left and rightcontrol handles, respectively.
 4. The safety cut-off system of claim 3,wherein said first and second forward presence levers extend generallyparallel to the corresponding left and right control handles, and arespaced away from the control handles in the OFF state.
 5. The safetycut-off system of claim 4, wherein each of said forward presence leversis pivoted about a point fixed on the corresponding control handle. 6.The safety cut-off system of claim 5, wherein reverse presence lever isdisposed generally parallel to a horizontal end portion of the handlebar.
 7. The safety cut-off system of claim 6, wherein said reversepresence lever is pivotable about a point fixed with respect to thehandle bar, such that said reverse presence lever is pivotable betweenthe OFF state, in which said reverse presence lever is spaced apart fromthe handle bar, and the ON state, in which said reverse presence leveris substantially adjacent the handle bar.
 8. The safety cut-off systemof claim 7, wherein said preventing means includes,(a) left and right,normally open, forward sensor switches for determining if eachcorresponding left and right forward presence lever is in the ON or OFFstate, wherein said left and right forward sensor switches are closedwhen the respective forward presence levers are in the ON state and areopen when the respective forward presence levers are in the OFF state,and (b) a normally open, reverse presence lever sensor switch,responsive to movement of said reverse presence lever, wherein saidreverse presence lever sensor switch is closed when said reversepresence lever is in the ON state and is open when said reverse presencelever is in the OFF state.
 9. The safety cut-off system of claim 8,wherein said preventing means further includes a normally closed,reverse gear sensor switch, which is open when reverse gear is engagedand is closed when reverse gear is not engaged, said reverse gear sensorswitch being in series with each of said forward sensor switches, whichare in parallel with one another.
 10. The safety cut-off system of claim9, wherein said preventing means further includes a normally closed,power take-off sensor switch which is closed if the power take-off unitis disengaged and is open if the power take-off unit is engaged.
 11. Thesafety cut-off system of claim 10, wherein said preventing meansincludes a circuit electrically connected with said forward sensorswitches, said reverse presence lever sensor switch, said reverse gearsensor switch, and said power take-off sensor switch, said circuitcausing a ground signal to be provided to a magneto, which providesspark to the motor, in order to prevent the motor from running, inresponse to the status of said sensor switches, wherein,when saidreverse gear sensor switch is closed, that is the lawn mower is inneutral or a forward gear, and said power take-off sensor switch isclosed, that is the power take-off unit is disengaged, there is noground signal to the magneto to prevent the motor from running, whensaid reverse gear sensor switch is closed, that is the lawn mower is inneutral or a forward gear, and said power take-off sensor switch isopen, that is the power take-off unit is engaged, the ground signal tothe magneto is prevented by any one of said forward sensor switches andsaid reverse presence lever sensor switch being closed, that is any oneof said forward presence levers and said reverse presence lever being inthe ON state, and when said reverse gear sensor is open, that is thelawn mower is in reverse gear, and irrespective of whether said powertake-off sensor switch is open or closed, that is the power take-offunit may be disengaged or engaged, the ground signal to the magneto toprevent the motor from running, is prevented only by said reversepresence lever sensor switch being closed, that is said reverse presencelever is in the ON state.
 12. The safety cut-off system of claim 1,wherein said reverse presence lever is mounted on a handle bar having agenerally horizontal end portion and said reverse presence lever isdisposed generally parallel and proximal to said generally horizontalend portion of said handle bar, and wherein said safety cut-off systemfurther comprises:a presence lever guard having a central plateextending away from a center position on the horizontal end portion ofthe handle bar, a reverse presence lever operatively mounted on thepower tool and manipulatable, by an operator, between an ON state and anOFF state, said reverse presence lever being biased to the OFF state,and preventing means, operatively connected to said presence levers, tothe motor and being responsive to said forward and reverse presencelevers, for preventing the motor from running,when the power tool is inneutral or a forward gear, the power take-off unit is engaged andneither said forward presence lever nor said reverse presence lever arein the ON state, and when the power tool is in a reverse gear and thereverse presence lever is not in the ON state.
 13. The safety cut-offsystem of claim 12, wherein said central plate is oriented generallyperpendicular to a direction of travel of the mower.
 14. The safetycut-off system of claim 13, wherein said guard includes a top plateextending from a top edge of said central plate, and substantially overa portion of said reverse presence lever.
 15. The safety cut-off systemof claim 14, wherein said guard and said end portion define a U-shapedspace and said reverse presence lever extends into said U-shaped space.16. A safety cut-off system for preventing the running of a motor of aself-propelled walk-behind power tool having a disengageable powertake-off unit for powering an auxiliary unit, wherein said power toolhas left and right drive wheels, forward and reverse gears, said safetycut-off system comprising:a first forward presence lever operativelymounted on the power tool and manipulatable, by an operator, between anON state and an OFF state, said forward presence lever being biased tothe OFF state; when said reverse gear sensor switch is closed, that isthe power tool is in neutral or a forward gear, and said power take-offsensor switch is open, that is the power take-off unit is engaged, theground signal to the magneto is prevented by any one of said forwardsensor switches and said reverse presence lever sensor switch beingclosed, that is any one of said forward presence levers and said reversepresence lever being in the ON state, and when said reverse gear sensoris open, that is the power tool is in reverse gear, and irrespective ofwhether said power take-off sensor switch is open or closed, that is thepower take-off unit may be disengaged or engaged, the ground signal tothe magneto to prevent the motor from running, is prevented only by saidreverse presence lever sensor switch being closed, that is said reversepresence lever is in the ON state.
 17. The safety cut-off system ofclaim 16, further comprising a second forward presence lever operativelyconnected to the power tool and manipulatable, by an operator, betweenan ON state and an OFF state, said second forward presence lever beingbiased to the OFF state, left and right control handles operativelyconnected to said left and right drive wheels, respectively, said firstand second forward presence levers corresponding to said left and rightcontrol handles, respectively.
 18. The safety cut-off system of claim17, wherein said first and second forward presence levers extendgenerally parallel to the corresponding left and right control handlesand are spaced away from the control handles in the OFF state.
 19. Thesafety cut-off system of claim 18, wherein each of said forward presencelevers is pivoted about a point fixed on the corresponding controlhandle.
 20. The safety cut-off system of claim 19, wherein said controlhandles are mounted on a handle bar of the power tool and said reversepresence lever is disposed generally parallel to said handle bar. 21.The safety cut-off system of claim 20, wherein said reverse presencelever is pivotable about a point fixed with respect to the handle bar,such that said reverse presence lever is pivotable between the OFFstate, in which said reverse presence lever is spaced apart from thehandle bar, and the ON state, in which said reverse presence lever issubstantially adjacent the handle bar.
 22. The safety cut-off system ofclaim 21, wherein said preventing means includes,(a) left and right,normally open, forward sensor switches for determining if eachcorresponding left and right forward presence lever is in the ON or OFFstate, wherein said left and right forward sensor switches are closedwhen the respective forward presence levers are in the ON state and areopen when the respective forward presence levers are in the OFF state,and (b) a normally open, reverse presence lever sensor switch,responsive to movement of said reverse presence lever, wherein saidreverse presence lever sensor switch is closed when said reversepresence lever is in the ON state and is open when said reverse presencelever is in the OFF state.
 23. The safety cut-off system of claim 22,wherein said preventing means further includes a normally closed,reverse gear sensor switch, which is open when reverse gear is engagedand is closed when reverse gear is not engaged, said reverse gear sensorswitch being in series with each of said forward sensor switches, whichare in parallel with one another.
 24. The safety cut-off system of claim23, wherein said preventing means further includes a normally closed,power take-off sensor switch which is closed if the power take-off unitis disengaged and is open if the power take-off unit is engaged.
 25. Thesafety cut-off system of claim 24, wherein said preventing meansincludes a circuit electrically connected with said forward sensorswitches, said reverse presence lever sensor switch, said reverse gearsensor switch, and said power take-off sensor switch, said circuitcausing a ground signal to be provided to a magneto, which providesspark to the motor, in order to prevent the motor from running, inresponse to the status of said sensor switches, wherein,when saidreverse gear sensor switch is closed, that is the power tool is inneutral or a forward gear, and said power take-off sensor switch isclosed, that is the power take-off unit is disengaged, there is noground signal to the magneto to prevent the motor from running.